1. Field of the Invention
The present invention relates to a system and a method for generating a microbubble-contained liquid, and a microbubble generator to be assembled in the system.
2. Background Art
Recently, a gas-supersaturated liquid containing microbubbles has been attracting attention as being a liquid usable widely in the fields of precision-machine cleaning, agriculture, oil separation, water purification, hot spring, etc. Existing systems for generating a microbubble-contained liquid use filters. Such filter-type microbubble-contained liquid generating systems are liable to fall in filter clogging, and they cannot keep their initial performance for a long term.
U.S. Pat. No. 6,293,529 discloses an apparatus for generating microbubbles. This apparatus includes a cylinder having a bulkhead with liquid holes at the upstream end thereof and a disk disposed opposite to the bulkhead, such that the bulkhead and the disk define a restriction passage. Thereby, a gas-dissolved liquid (a liquid containing dissolved gas) is forced to pass through the restriction passage to generate a large quantity of microbubbles in the liquid.
It is known that microbubbles had better be smaller and smaller in diameter to (1) absorb suspended solids (solids suspended in water) more effectively, (2) increase the contact area between water and air and elongate the duration of time where the bubbles drift densely in water to contribute to more efficient decomposition of organic matter, and (3) penetrate more deeply into objects to be cleaned and thereby enhance the cleaning effect.
In the apparatus disclosed in U.S. Pat. No. 6,293,529, however, the microbubbles contained in the gas-supersaturated liquid are relatively large in diameter. So, the microbubble-contained liquid generated by the apparatus is applicable only to a limited field of industry.